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<H1 class="no-header">curs_scr_dump 3x 2025-01-18 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>                Library calls               <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>scr_dump</STRONG>,  <STRONG>scr_restore</STRONG>,  <STRONG>scr_init</STRONG>, <STRONG>scr_set</STRONG> - read/write a <EM>curses</EM> screen
       from/to a file


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>

       <STRONG>int</STRONG> <STRONG>scr_dump(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>scr_restore(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>scr_init(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>scr_set(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       <EM>curses</EM> provides applications the ability to write the contents  of  the
       screen  to  a  file and read them back.  To read/write a window (rather
       than the whole screen) from/to a file, use <STRONG><A HREF="curs_util.3x.html">getwin(3x)</A></STRONG>  and  <STRONG><A HREF="curs_util.3x.html">putwin(3x)</A></STRONG>,
       respectively.


</PRE><H3><a name="h3-scr_dump">scr_dump</a></H3><PRE>
       <STRONG>scr_dump</STRONG>  writes  to  <EM>filename</EM>  the contents of the virtual screen; see
       <STRONG><A HREF="curs_variables.3x.html">curscr(3x)</A></STRONG>.


</PRE><H3><a name="h3-scr_restore">scr_restore</a></H3><PRE>
       <STRONG>scr_restore</STRONG> updates  the  virtual  screen  to  match  the  contents  of
       <EM>filename</EM> (if validly written with <STRONG>scr_dump</STRONG>).  <EM>curses</EM> does not perform a
       refresh;  after  making  any  desired  changes,  call  <STRONG><A HREF="curs_refresh.3x.html">doupdate(3x)</A></STRONG>  or
       similar.


</PRE><H3><a name="h3-scr_init">scr_init</a></H3><PRE>
       <STRONG>scr_init</STRONG>  reads <EM>filename</EM>, using it to initialize <EM>curses</EM> data structures
       describing the state of  the  terminal  screen.   <EM>curses</EM>  then,  if  it
       decides  the  terminal  state  is  valid,  bases its next update of the
       screen on this information rather than clearing it  and  starting  from
       scratch.

       <EM>curses</EM>  regards  the terminal as in an invalid state for computation of
       updates based on the contents of <EM>filename</EM> if

       <STRONG>o</STRONG>   <EM>curses</EM> knows that the  terminal  has  been  written  to  since  the
           preceding <STRONG>scr_dump</STRONG> call, or

       <STRONG>o</STRONG>   the  terminal  type supports the <EM>terminfo</EM> capabilities <STRONG>exit_ca_mode</STRONG>
           (<STRONG>rmcup</STRONG>) or <STRONG>non_rev_rmcup</STRONG> (<STRONG>nrrmc</STRONG>).

       Either of the foregoing conditions means that <EM>curses</EM> cannot assume that
       the  terminal's  contents  match their representation in <EM>filename</EM>.  The
       former is due to  terminal  features  (such  as  <STRONG>xterm(1)</STRONG>'s  "alternate
       screen")  that  couple  cursor-positioning  mode  with a local cache of
       screen contents.  <EM>curses</EM> cannot know whether the terminal is displaying
       from that local cache at the time the application calls <STRONG>scr_init</STRONG>, so it
       makes a pessimistic assumption that a  full  redraw  is  required;  see
       subsection "Cursor Motions" of <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>.

       <STRONG>scr_init</STRONG>  could  be  used  after  <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG> or <STRONG>system(3)</STRONG> to share the
       screen with another process that has done a <STRONG>scr_dump</STRONG> after  <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG>.
       An   application  that  supports  suspending  its  state  on  exit  and
       subsequent resumption upon  later  execution  might  use  <STRONG>scr_dump</STRONG>  and
       <STRONG>scr_init</STRONG> thus.


</PRE><H3><a name="h3-scr_set">scr_set</a></H3><PRE>
       <STRONG>scr_set</STRONG>  combines  <STRONG>scr_restore</STRONG> and <STRONG>scr_init</STRONG>, synchronizing the contents
       of <EM>filename</EM> with the virtual screen.  It can be regarded  as  a  screen
       inheritance function; consider a real-time screen-sharing application.


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.

       In  <EM>ncurses</EM>,  each  function  returns  <STRONG>ERR</STRONG>  if it cannot open <EM>filename</EM>.
       <STRONG>scr_init</STRONG>, <STRONG>scr_restore</STRONG>, and  <STRONG>scr_set</STRONG>  return  <STRONG>ERR</STRONG>  if  the  contents  of
       <EM>filename</EM> are invalid.


</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
       <STRONG>scr_init</STRONG>, <STRONG>scr_restore</STRONG>, and <STRONG>scr_set</STRONG> may be implemented as macros.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       X/Open Curses Issue 4 describes these functions.  It specifies no error
       conditions for them.

       SVr4 omitted the <EM>const</EM> qualifiers.

       SVr4 documentation describes <EM>scr</EM><STRONG>_</STRONG><EM>init</EM> such that the dump data  is  also
       considered  invalid  "if the time-stamp of the tty is old" but does not
       define "old".

       As of 2024, <EM>PDCurses</EM> provides these functions.  NetBSD <EM>curses</EM> does not.

       Other implementations of <EM>curses</EM> store the window in binary form,  which
       makes  the  dump  dependent  upon  the  <EM>curses</EM>  library's internal data
       structures.  <EM>ncurses</EM> avoids  this  drawback  by  storing  the  dump  in
       textual  form,  allowing  more flexible use of the data.  For instance,
       the <EM>scr</EM><STRONG>_</STRONG><EM>restore</EM> of SVr4 <EM>curses</EM> requires that the dumped window have the
       same  dimensions  as the restored window.  <EM>ncurses</EM> uses its <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>
       extension to adjust the restored window size.


</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
       SVr3 (1987) introduced <EM>scr</EM><STRONG>_</STRONG><EM>dump</EM>,  <EM>scr</EM><STRONG>_</STRONG><EM>init</EM>,  and  <EM>scr</EM><STRONG>_</STRONG><EM>restore</EM>.   SVr3.1
       added <EM>scr</EM><STRONG>_</STRONG><EM>set</EM>.


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>,
       <STRONG>system(3)</STRONG>, <STRONG><A HREF="scr_dump.5.html">scr_dump(5)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>, <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>



ncurses 6.5                       2025-01-18                 <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>
</PRE>
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<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-scr_dump">scr_dump</a></li>
<li><a href="#h3-scr_restore">scr_restore</a></li>
<li><a href="#h3-scr_init">scr_init</a></li>
<li><a href="#h3-scr_set">scr_set</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
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